| Digital TV is broadcast television industry’s technological revolution driven digital TVindustry has become an important part of our country and the global information industry.Compared with the traditional analog television technology, digital TV in the video and audioquality, anti-jamming performance, the spectrum utilization rate, realizing the conditionalaccess and supporting value-added services and so on have an unparalleled advantage, thisalso is in recent years the rise in the world of digital TV the prime cause of tide. Theconditional access system as one of the core technologies of the digital TV industry operation,is the basic protection to realize digital television services and various value-added services,and plays a decisive role to promote the vigorous development of the digital TV industry.China’s digital cable TV transmission is adopted the DVB-C standard. DVB useMPEG-2standard as the source coding standard, and defines the technical specification ofdigital television multiplexing, scrambling, transfer, interface and interactive applications etc.Conditional access system is used to control the subscriber access to the broadcast service orprogram receiving system, namely, the subscriber can only watch authorized broadcastingservice or program. DVB conditional access technical standards defined the simulcrypt modeand multi-encryption mode, simulcrypt mode refers to two or more CA systems with anMPEG-2transport stream encrypted scrambling, this is also the Chinese cable digital TVbroadcast access system specified in the standard encryption mode.The subject of this thesis is the study of the realization of the the simulcrypt mode of theconditional access system based on the DVB-C standard. In this paper, on the basic researchand application of foreign and domestic conditional access system, conducts a detailedanalysis of the MPEG-2and DVB standards with the relevant provisions of the conditionalaccess system,and focus on the study conditional access system of the basic principles as wellas the key technology, including the CA front-end system architecture and its components, theterminal system, encryption and decryption algorithm, common scrambling algorithm,security mechanisms, the simulcrypt mode and multi-encryption mode ect. Then throughsimulcrypt system of digital cable TV market demand research and analysis, from thefunctional requirements and performance needs of conditional access systems for digital cable television in the program scrambling and descrambling, data encryption and decryption, datacommunications and simulcrypt synchronization operations demand, proposed a simulcryptsystem of design, including the simulcrypt modular architecture of the system design, modulecommunication interface design, the timing of ECM/EMM and broadcast design, securityperformance design and introduction of simulcrypt system concrete realization with theapplication deployment instance of TFCAS.Finally，the design with simulcryt CA system wastested and verified. |
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